1. Field of the Invention
The present invention relates to a circuit board for use in various electronic devices and joint boxes for connecting, dividing and joining various kinds of electric wires, a method of manufacturing such a circuit board, and also relates to a joint box including such circuit boards.
2. Related Art Statements
There have been known various types of joint boxes. For instant, in Document 1 (Japanese Patent Publication Kokai Hei 10-243526 of Japanese Patent Application assigned to the same assigner to which the instant application has been assigned), there is disclosed a known joint box in which a plurality of FFC (flexible flat cables) are stacked one another and are subjected to a rather complicated circuit constituting treatment. In this known joint box, a conductive foil 1 having a given circuit pattern formed therein is sandwiched between a pair of insulating sheets 2 to form a flat cable layer 3 as illustrated in FIG. 28.
A plurality of flat cable layers 3 are stacked one another and a plurality of common holes 4 are formed in such a manner that a conductive foil 1 of a given flat cable layer 3 is exposed within respective common holes 4. Then, an exposed portion of the relevant conductive foil 1 is fused to a lower end of a connection terminal 5 provided on the uppermost flat cable layer 3.    Document 1: Japanese Patent Application Kokai Hei 10-243526